Taking up a fire door as an example, an inside of a structure such as a building is divided into fire control areas, and in order to prevent fire from spreading throughout the structure by these fire control areas, a fire door, a fire shutter or the like is provided capable of being opened/closed in the passage or the like so as to be urged to be closed all the time in a case of fire.
Such fire doors used to be called “T e-A fire door” and “Type-B fire door”, and designated fire preventive equipment/fire preventive equipment is specified to have a structure through which fire does not penetrate for 1 hour or more or 20 minutes or more in the case of usual fire. In addition, in order to be reliably closed in case of fire, only two types of structures, that is, an all-time closed type fire door which is open only when it is opened by a particular intension of a person by a door closer or the like and is closed all the time other than that and an anytime closed type fire door which is closed when fire is detected are allowed. The all-time closed type fire door is not locked even if it is opened largely unlike a general door closer but is closed without fail if the person releases the hand. It is also called “all-time closed” as abbreviation.
As described above, whether it is the all-time closed fire door or the anytime closed fire door, the fire door is closed by an urging force of urging means for preventing spread in case of fire, the door is required to be easily opened manually in order to ensure evacuation at fire and to allow firefighting activities.
On the other hand, evacuation activities are assisted safely and reliably by providing a natural smoke exhaustion facility or a mechanical forced smoke exhaustion facility and by discharging smoke filled in a room or passage at fire by the smoke exhaustion facilities. But if the mechanical smoke exhaustion facility is operated, a pressure inside the room becomes negative, and opening of the fire door needs a considerable force. Such situation hinders evacuation activities of powerless people such as elderly people, children and the like, whereby human lives are put at risk and moreover, rescue activities are interfered. Similar cases are caused by an operation of an exhaustion fan of a housing unit with high sealing degree.
In order to prevent such harmful effects, the following Patent Literature has an object to provide a fire door device which eliminates a pressure difference so as to facilitate evacuation only by an opening operation using a door knob and reliably plays a role as a fire door.